MUSCULAR AND ALLIED SYSTEMS. 87 



c. 



MUSCULAR AND ALLIED SYSTEMS. 



PLANTS. 



C. 1. Two branches of Desmodium gyrans showing the diarnal 

 and nocturnal positions of the leaves. There is no special- 

 ised motile organ, but the entire leaf- stalk (petiole) is 

 straight during daylight from the uniform turgescence of 

 its cells. In the dark, the cells of the upper half of the 

 leaf-stalk becoming more turgid, causes the downward 

 curvature. 



Sachs, Physiology of Plants (Eng. trans.), p. 623. 



C. 2. Portion of a ternate leaf of Erytlirina corallodendron, to 

 show the part between the leaflet and petiole by which 

 the motion of the leaflets takes place after sunset. 0. C. 28. 



"There is an action in plants which appears to be the contrary of 

 expansion ; it may be considered as a relaxation, or an action of 

 those parts antagonizing the others which acted through the day, 

 or at other periods, and it takes place at the time these other 

 parts cease to act. 



"This action has hitherto been considered as analogous to 

 sleep in animals ; whereas, sleep is a total loss of the sensitive 

 principle, and all the actions dependent on volition for the time ; 

 and, therefore, can only take place in animals endowed with 

 sensation. It is rather a defect in the animal, than an action, 

 or the exertion of a principle." John Hunter, MS. Croonian 

 Lectures, No. 1. 



[The various actions that take place in plants at the close of 

 day, are described by Linnasus in Amcenitates Academicce, iv. 

 p. 333, under the title Somnus Plantarum.~\ 



Hunterian. 



C. 3. Leaves of Hcdysarum gyrans, in w r hich the small lateral 

 leaflets have a power of moving up and down, with 

 a varying degree of velocity, and without any mutual 

 uniformity or co-operation. These motions take place 

 independent of external stimulus. 0.0. .31. Hunterian. 



